Control device of compressor, electronic control valve used for same, electric compressor comprising same

ABSTRACT

A control device of a compressor includes a piston which reciprocates by a swash plate, a crankcase receiving the swash plate mounted such that an inclination angle thereof is variable, a discharge chamber from which a compressed working fluid is discharged, a suction chamber sucking the working fluid to be compressed, a first communication channel connecting the suction chamber and the crankcase, a second communication channel connecting the discharge chamber and the crankcase, and a control valve which selectively opens and closes the first communication channel and the second communication channel. The control device includes a suction pressure sensor measuring a pressure of the suction chamber, a valve control unit determining a target suction pressure on the basis of the value measured by the suction pressure sensor and a set temperature, and a valve driving unit controlling the opening degree of the control valve to achieve the target suction pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a United States nation phase patent application based on PCT/KR2019/000731 filed on Jan. 18, 2019, which claims the benefit of Korean Patent Application No. 10-2018-0131392 filed on Oct. 31, 2018 and Korean Patent Application No. 10-2018-0010891 filed on Jan. 29, 2018, the entire disclosures of which are hereby incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a control device for controlling the operation of a compressor, an electronic control valve used for the same, and the compressor including them.

BACKGROUND ART

In general, a refrigerant compression cycle device for providing heating and cooling is provided in a vehicle air-conditioning system. The refrigerant compression cycle device is equipped with a compressor which compresses and circulates a refrigerant. A variable displacement swash plate type compressor is being widely used.

The variable displacement swash plate type compressor is configured such that a stroke of a piston can be adjusted according to an inclination angle of the swash plate which rotates with an adjustable angle with respect to a housing. The inclination angle of the swash plate may be adjusted by a difference between a pressure in a crankcase and a pressure in a suction chamber. That is, when a high-pressure refrigerant in a discharge chamber is introduced into the crankcase to increase the pressure of the crankcase, the swash plate is disposed perpendicular to the main axis, thereby reducing the stroke of the piston. On the contrary, when the pressure in the crankcase is reduced, the swash plate is disposed to be inclined and the stroke of the piston is increased to increase the discharge flow rate of the refrigerant.

The crankcase is always in communication with the suction chamber, and the swash plate type compressor is provided with a control valve for connecting the crankcase and the discharge chamber to control the flow rate of the high-pressure refrigerant from the discharge chamber. The control valve is classified into a mechanical control valve and an electronic control valve according to its operating method. The mechanical control valve is operated by pressure differences in the suction chamber, the crankcase, and the discharge chamber without external control. The mechanical control valve works together with a so-called “internal control type variable compressor”, and controls the outlet temperature of an evaporator to be maintained at 1° C. to 2° C. Therefore, there are disadvantages that the width of the temperature control is small and a separate clutch for on/off of the compressor is required.

On the other hand, the electronic control valve is used together with a so-called “external control type variable compressor” and includes an operating rod therein which is driven by an electronic actuator such as a solenoid, etc. The operating rod moves the valve bodies in accordance with the on/off of the solenoid, and not only the discharge chamber, the crankcase, and the suction chamber can be thereby selectively communicated but also their opening degrees can be adjusted. Due to this, the external control type variable compressor can adjust the outlet temperature of the evaporator in the range of 1° C. to 12° C., so that it is possible both to optimize the operation in accordance with the cooling load, thereby reducing power consumption, and to operate without a clutch, thereby reducing the manufacturing cost.

Here, a control unit for controlling the electronic control valve is provided in the vehicle air-conditioning system. The control unit controls the opening degree of the valve in consideration of external environmental conditions and the indoor temperature set by the user and thereby changes the stroke of the piston, so that the indoor space can be maintained at the set temperature.

Recently, research is being devoted to the reduction of the power consumption of the air conditioning system mounted on the vehicle, in particular, the power consumption of the compressor, in connection with problems such as strengthening of environmental regulations, the limit of the mileage of an electric vehicle, etc.

SUMMARY

The embodiment of the present invention is designed to overcome the above-described disadvantages of the prior art and is to provide a control device for a compressor that can control the operation of the compressor more precisely in accordance with the operation state of the compressor.

The embodiment of the present invention is to provide an electronic control valve that can be used in the control device described above.

The embodiment of the present invention is to provide a compressor including the electronic control valve described above.

One embodiment is a control device of a compressor, which includes a piston which reciprocates by a swash plate, a crankcase for receiving the swash plate which is mounted such that an inclination angle thereof with respect to a rotational shaft is variable, a discharge chamber from which a compressed working fluid is discharged, a suction chamber for sucking the working fluid to be compressed, a first communication channel for connecting the suction chamber and the crankcase, a second communication channel for connecting the discharge chamber and the crankcase, and a control valve which selectively opens and closes the first communication channel and the second communication channel. The control device of the compressor includes: a suction pressure sensor for measuring a pressure of the suction chamber, a valve control unit for controlling opening degrees of the first communication channel and the second communication channel within the control valve by comparing a suction pressure value measured by the suction pressure sensor and a target suction pressure; and a valve driving unit for operating an actuator which moves a valve body of the control valve to a determined position from the valve control unit to achieve the target suction pressure.

Another embodiment is a control valve which includes: a casing in which a space portion is formed therewithin and an electronic actuator is provided on one side end thereof; a valve body which is mounted to move within the casing; a first through hole which communicates with the space portion of the casing and a suction chamber of a compressor on which the control valve is mounted; a fourth through hole which communicates with the space portion of the casing and a discharge chamber of the compressor on which the control valve is mounted; and Second and third through holes which communicate with the space portion of the casing and a crankcase of the compressor on which the control valve is mounted. The second and third through holes are selectively opened and closed while the valve body moves along a longitudinal direction of the valve body.

Further another embodiment is a compressor which includes: the above control valve; a rear housing in which the control valve is received and in which the suction chamber and the discharge chamber are formed respectively; a cylinder housing which comprises a plurality of cylinder bores radially formed therein and is coupled to the rear housing; and a front housing which is coupled to the cylinder housing and comprises the crankcase in which the swash plate is disposed therein. A first communication channel which communicates the crankcase and the suction chamber is defined by the cylinder housing, the rear housing, the second through hole, and the first through hole. A second communication channel which communicates the crankcase and the discharge chamber is defined by the cylinder housing, the rear housing, the fourth through hole, and the third through hole.

Compared to a prior art in which an inclination angle of a swash plate is controlled by opening and closing a flow path between the discharge chamber and the crankcase while always communicating the crankcase and the suction chamber, according to the features of the present invention, by controlling the inclination angle of the swash plate by selectively opening and closing a flow path between the crankcase and the suction chamber and the flow path between the discharge chamber and the crankcase, a discharge amount of a compressed refrigerant can be increased, thereby improving the efficiency of the compressor. That is, since a suction pressure is directly controlled, even if the pressure of the crankcase is increased by the refrigerant leaking during a compression process, this can be overcome by operating the control valve. Therefore, an orifice flow path, which is the cause of conventional efficiency degradation, can be eliminated or minimized.

DESCRIPTION OF DRAWINGS

FIG. 1 is a cross sectional view showing an internal structure of a swash plate type compressor to which an embodiment of an electronic control valve according to the present invention is applied;

FIG. 2 is an enlarged cross sectional view of the control valve shown in FIG. 1;

FIG. 3 is an enlarged cross sectional view of a portion of a valve body of FIG. 2;

FIG. 4 is a cross sectional view showing a state in which a first communication channel is fully opened in the embodiment shown in FIG. 2;

FIG. 5 is a graph showing a change in the degree of opening and closing of the first and second communication channels according to a movement of the valve body in the embodiment shown in FIG. 2;

FIG. 6 is a graph showing a change in suction pressure and a change of a valve opening degree in the process of increasing an inclination angle of the swash plate in the embodiment shown in FIG. 1;

FIG. 7 is a graph showing the change in the suction pressure and the change of the valve opening degree in the process of reducing the inclination angle of the swash plate in the embodiment shown in FIG. 1;

FIG. 8 is a block diagram schematically showing a configuration of an embodiment of a control device for controlling the operation of the compressor shown in FIG. 1;

FIG. 9 is a block diagram schematically showing a configuration of another embodiment of the control device for controlling the operation of the compressor shown in FIG. 1; and

FIG. 10 is a flowchart showing a process of controlling the suction pressure in the control device shown in FIG. 8.

MODE FOR INVENTION

Hereinafter, an embodiment of an electronic control valve according to the present invention and a swash plate type compressor including the same according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a center bore 11 is formed to pass through the center of a cylinder housing 10 of a swash plate type compressor (hereinafter, referred to as a “compressor”) according to an embodiment of the present invention. A plurality of cylinder bores 13 are formed to surround radially the center bore 11 and pass through the cylinder. A piston 15 is installed to be movable within the cylinder bore 13 and compresses a refrigerant in the cylinder bore 13.

Meanwhile, a front housing 20 is installed on one end of the cylinder housing 10. The front housing 20 cooperates with the cylinder housing 10 to form a crankcase 21 therein.

A rear housing 30 is installed on the other end of the cylinder housing 10, that is, on a side opposite to the side on which the front housing 20 is installed. A suction chamber 31 is formed in the rear housing 30 in such a manner as to selectively communicate with the cylinder bore 13. Here, the suction chamber 31 serves to transfer the refrigerant to be compressed to the inside of the cylinder bore 13.

A discharge chamber 33 is formed in the rear housing 30. The discharge chamber 33 is formed in an area corresponding to the outside of a surface facing the cylinder housing 10 of the rear housing 30. The discharge chamber 33 is a place where the refrigerant compressed in the cylinder bore 13 is discharged and temporarily stays. A control valve 100 is provided on one side of the rear housing 30. The control valve 100 serves to control an angle of a below-described swash plate 48 by controlling opening degrees of a flow path between the crankcase 21 and the suction chamber 31 and of a flow path between the discharge chamber 33 and the crankcase 21.

On the other hand, a rotational shaft 40 is rotatably installed to pass through the center bore 11 of the cylinder housing 10 and a shaft hole 23 of the front housing 20. The rotational shaft 40 rotates by a driving force transmitted from an engine. The rotational shaft 40 is rotatably installed in the cylinder housing 10 and in the front housing 20 by a bearing 42.

Also, a rotor 44 is provided in the crankcase 21. The rotational shaft 40 passes through the center of the rotor 44 and rotates integrally with the rotor 44. Here, the rotor 44 is fixedly installed on the rotational shaft 40 in an approximate disk shape, and a hinge arm (not shown) to protrude from one side of the rotor 44.

The swash plate 48 is installed on the rotational shaft 40 in such a way to be hinged to the rotor 44 and rotate together. The swash plate 48 is installed to have an angle variable with respect to the rotational shaft 40 in accordance with a discharge capacity of the compressor. That is, the swash plate 48 is between a state of being orthogonal to a longitudinal direction of the rotational shaft 40 and a state of being inclined at a predetermined angle with respect to the rotational shaft 40. An edge of the swash plate 48 is connected to the pistons 15 through a shoe (not shown). That is, the edge of the swash plate 48 is connected to a connecting portion 17 of the piston 15 through the shoe, so that the piston 15 linearly reciprocates in the cylinder bore 13 by the rotation of the swash plate 48.

Meanwhile, an anti-inclination spring (not shown) providing an elastic force is provided between the rotor 44 and the swash plate 48. The anti-inclination spring is installed to surround the outer surface of the rotational shaft 40, and provides an elastic force in a direction in which an inclination angle of the swash plate 48 decreases. A swash plate stopper 58 is formed to protrude from one side of the swash plate 48. The swash plate stopper 58 functions to limit the degree to which the swash plate 48 is inclined with respect to the rotational shaft 40.

Also, a pulley assembly 60 is mounted on one side end of the rotational shaft 40. The pulley assembly 60 is mounted to receive a rotational force through a belt from another power source such as an engine of a vehicle. In addition, a clutch assembly 62 is installed on the pulley assembly 60. The clutch assembly 62 includes a coil and a core 62 a which are installed within the pulley assembly 60 and a disk 62 b which is installed outside the pulley assembly 60.

Here, since any type of a commonly known clutch assembly can be employed, a detailed description thereof will be omitted. In any case, in the clutch assembly 62, the disk 62 is brought into close contact in accordance with a current applied to the coil and the core 62 a, so that the rotational force that is transmitted to the pulley is thereby also transmitted to the rotational shaft 40. The greater the current that is applied, the greater the degree to which the disk is brought into close contact, so that the transmitted rotational force is transmitted to the rotational shaft without loss. If the current is low, only a portion of the transmitted force is transmitted to the rotational shaft. Therefore, torque or the force applied to the rotational shaft which drives the compressor can be controlled according to the degree to which the current is applied.

When no current is applied to the clutch, only the pulley rotates and the rotational shaft does not rotate. Therefore, unnecessary compressor operations can be prevented, which is helpful to the improvement of efficiency. In addition, when the inclination angle of the swash plate is increased and thus the stroke of the piston is increased, required torque is also increased. When the inclination angle of the swash plate is decreased and thus the stroke of the piston is decreased, the required torque is also decreased. Therefore, the force that is consumed by the compressor can be minimized by appropriately controlling the torque transmitted according to the inclination angle of the swash plate. This leads to the increase in overall efficiency of the vehicle.

Meanwhile, the control valve 100 is received within a valve receiving portion 34 formed in the rear housing 30. First to fourth internal flow paths are formed in the valve receiving portion 34. The first to fourth internal flow paths 35 a, 35 b, 35 c, and 35 d are respectively connected to later-described first to fourth through holes of the control valve.

Here, the first through hole 110 c is formed to communicate the inside of the control valve and the suction chamber of the compressor. The second through hole 110 a 1 and the third through hole 110 a 2 are formed to communicate the inside of the control valve and the crankcase of the compressor. The fourth through hole 110 b is formed to communicate the inside of the control valve and the discharge chamber of the compressor. In addition, the first internal flow path 35 a communicates with the suction chamber 31. The fourth internal flow path 35 d communicates with the discharge chamber 33. The second and third internal flow paths 35 b and 35 c are connected to the crankcase 21, and they are not connected to each other until they reach the crankcase.

A channel leading to the crankcase 21-the second internal flow path 35 b-the second through hole-the control valve casing-the first through hole-the first internal flow path 35 a-the suction chamber 31 is defined as a first communication channel P1. A channel leading to the discharge chamber 33-the fourth internal flow path 35 d-the fourth through hole-the control valve casing-the third through hole-the third internal flow path 35 c-the crankcase 21 is defined as a second communication channel P2. They are respectively indicated by arrows in FIG. 1, and the refrigerant flows always in the direction indicated by the arrows due to the pressure difference between the suction chamber, the crankcase and the discharge chamber. A plurality of O-rings are disposed on the outer circumferential surface of the control valve and block the leakage of the refrigerant between the control valve casing and an inner wall of the valve receiving portion 34.

In FIG. 1, the second and third internal flow paths do not overlap each other until they reach the crankcase. However, in some cases, it is possible to consider that they are integrated into one within the rear housing or within the cylinder housing and then are extended to the crankcase.

When the first communication channel is opened, the crankcase and the suction chamber communicate with each other and then the pressure of the crankcase is lowered, thereby increasing the inclination angle of the swash plate. Consequently, the stroke of the piston is increased. On the contrary, when the second communication channel is opened, the crankcase and the discharge chamber communicate with each other and then the pressure of the crankcase is increased, thereby reducing the inclination angle of the swash plate. Consequently, the stroke of the piston is reduced.

The control valve 100 will be described in detail with reference to FIGS. 2 and 3. Referring to FIG. 2, the control valve 100 includes a cylindrical casing 110 the diameter of which decreases toward the bottom of FIG. 2. A plurality of grooves are formed on the outer circumferential surface of the casing 110. The aforementioned O-rings 102 are fitted into the grooves, respectively. As described above, the O-rings are installed to prevent the refrigerant from leaking into a gap between the casing of the control valve and the inner wall of the valve receiving portion 34.

A space portion is formed within the casing 110. The refrigerant in the suction chamber, the crankcase, and the discharge chamber is selectively introduced into the space portion in accordance with the operation states of the valve. Specifically, the second and third through holes 110 a 1 and 110 a 2 communicating with the crankcase 21 are disposed approximately in the center of the casing 110. The first through hole 110 c communicating with the suction chamber 31 is disposed above the second and third through holes 110 a 1 and 110 a 2. The fourth through hole 110 b communicating with the discharge chamber 33 is disposed at the lowermost end thereof.

Here, a plurality of the first to third through holes are radially arranged on a side of the casing 110, and the fourth through hole is different from the first to third through holes in that the fourth through hole is formed in a lower end portion of the casing 110. Such a shape provides an advantage capable of reducing the length of the casing 110. When the space is less restricted, the fourth through hole may be arranged in the same shape as those of the other through holes. A filter 112 is installed in the fourth through hole 110 b to block foreign substances remaining within the discharge chamber from being introduced together with the refrigerant.

An electromagnetic actuator (not shown) is installed on the casing 110. The electromagnetic actuator generates an electromagnetic force that varies depending on the magnitude of the current applied through a connector 108. The electromagnetic force moves a later described valve body. However, the shape of the electronic actuator in the present invention is not necessarily limited to the illustrated shape. It is also possible to consider an example of utilizing any means, for example, a piezoelectric element, etc., capable of controlling the movement by applying a voltage, or a means, for example, a stepper actuator, which controls the movement by applying a rotating magnetic field. In addition, an elastic means which applies, together with the electromagnetic actuator, an upward force to the valve body with reference to FIG. 2 is further provided. The operation of the elastic means will be described later.

The valve body 120 has an approximate cylindrical shape that is disposed to be movable up and down in contact with the inner surface of the casing 110. In addition, a needle 122 having a smaller diameter is formed on the bottom surface of the valve body 120. The valve body 120 faces the aforementioned second through hole 110 a 1 and controls the opening degree of the second through hole in accordance with the facing position while facing the aforementioned second through hole 110 a 1. The needle 122 faces the third through hole 110 a 2 and controls the opening degree of the third through hole in accordance with the facing position while facing the third through hole 110 a 2.

A tapered surface 122 a is formed on the lowermost end of the needle 122. Thus, as the tapered surface 122 a of the needle approaches upwards the third through hole, the opening degree of the third through hole increases at a relatively slow speed at the beginning of opening after closing, and increases more rapidly as the movement progresses. This not only prevents pulsation is generated by a rapid increase of the opening degree in the early stage of controlling the opening degree, but also allows more precise control of the opening degree. Likewise, a tapered surface 124 is also formed on the upper surface of the valve body 120. Accordingly, the opening degree of the second through hole can be also controlled more precisely.

Here, the first and fourth through holes always remain in an open state regardless of the position of the valve body 120. However, the opening degrees of the second and third through holes vary according to the position of the valve body 120. This will be described later.

On the other hand, the valve body 120 is in a state of having moved upwards as much as possible with reference to FIG. 2 by the elastic force of the aforementioned elastic means in a state that the current is not applied to the electromagnetic actuator. In this state, an internal pressure Pc of the crankcase 21 is almost the same as a discharge pressure Pd of the discharge chamber 33. When the current is applied to the electromagnetic actuator, the valve body 120 moves downward so that the opening degrees of the second and third through holes are changed.

Specifically, as the valve body moves from the uppermost end to the lower end, the opening degree of the second through hole increases and the opening degree of the third through hole decreases. Thus, the first communication channel is further opened and the second communication channel is closed. Here, the inner space of the casing 110 is formed to have different inner diameters in order to match the diameter of the needle and the valve body, thereby having a stepped portion. Therefore, as shown in FIG. 2, a space 104 is formed between the valve body 120 and the stepped portion, and a part of the refrigerant and oil are trapped in the space 104. They act as a resistance hindering the movement of the valve body, so that responsiveness is degraded and the actuator is required to have a greater operating force.

Accordingly, as shown in FIG. 3, an internal flow path having an inlet 127 formed in the lower portion (see FIGS. 2 and 3) of the valve body 120 and an outlet 126 on a side of the valve body is additionally formed. The internal flow path serves to transfer the refrigerant and oil collected in the space 104 to another space in the casing, and thus, to reduce the resistance associated with the movement of the valve body by transferring the refrigerant and oil collected in the space 104 to another space in the casing. The internal flow path may be further formed in the casing 110.

FIG. 4 shows, as described above, a state in which a current is applied to the control valve and the valve body is lowered, thereby opening the second through hole and closing the third through hole. In the state of FIG. 4, the first communication channel P1 is opened to increase the stroke of the piston. That is, as the valve body 120 moves the top to the bottom, the third through hole is closed and the second through hole is opened. Referring to FIG. 5, a horizontal axis represents a moving distance of the valve body and a vertical axis represents the opening degrees of the first and second communication channels.

The left area of the graph shows the second communication channel P2 is gradually closed as the valve body moves downward. The right area of the graph shows the first communication channel P1 is gradually opened as the valve body moves downward. In the area near the origin, a section in which the opening and closing of the first and second communication channels are reversed occurs. It is noted that a section in which two communication channels are opened at the same time does not exist.

If there is a section in which the two communication channels are simultaneously opened, the refrigerant introduced into the crankcase from the discharge chamber flows as it is into the suction chamber without contributing to the adjustment of the inclination angle of the swash plate, so that the loss is greatly increased. Therefore, in the embodiment, such a loss can be minimized by removing the section in which the first and second communication channels are opened at the same time.

In addition, in the embodiment, the control valve is operated in a section marked as “control section” without being utilized in all the sections shown in FIG. 5. Most control sections are arranged in the section that controls the opening and closing of P1. A method of controlling the control valve and the compressor will be described later.

FIG. 6 is a graph showing a change in suction pressure and a change of a valve opening degree in the process of increasing the stroke of the piston. When a cooling load is increased by user's choice or other causes, the stroke of the piston should be increased as described above. To this end, a control unit determines a suction pressure at which the corresponding stroke can be obtained and sets the suction pressure as a target suction pressure. Alternatively, the set suction pressure value may be reduced by a higher control unit included in a vehicle air conditioner and transmitted to the compressor control unit.

Information on the target suction pressure value may be also transmitted by a duty cycle of a PWM voltage signal, a current resulting from the PWM duty cycle, or a digital bus such as LIN or CAN communication. Further, this is illustrative and not necessarily intended to be limiting.

The set suction pressure value is indicated by a dotted line in FIG. 6. At a point of time when the control is started, that is, when the set value is changed to a lower value, a current is applied or increased to the electromagnetic actuator in accordance with the instruction of the control unit, and accordingly, the opening degree of the first communication channel is instantaneously increased.

Accordingly, the measured suction pressure is lowered. However, due to physical limitations, the measured value cannot follow the set value as it is, and follows with a time delay to some extent. In addition, the suction pressure is temporarily lower than the target value due to the flow characteristics of the refrigerant, and the valve body is repeatedly moved up and down. Finally, the suction pressure converges to the target value.

FIG. 7 is a graph showing the change in the suction pressure and the change of the valve opening degree in the process of reducing the stroke of the piston. When a cooling load is reduced by user's choice or other causes, the stroke of the piston should be reduced as described above. To this end, the control unit determines a suction pressure at which the corresponding stroke can be obtained and sets the suction pressure as a target suction pressure. Alternatively, the set suction pressure value may be increased by a higher control unit included in a vehicle air conditioner and transmitted to the compressor control unit. The set suction pressure value is indicated by a dotted line in FIG. 7. At a point of time when the control is started, that is, when the set value is changed to a higher value, the current applied to the electromagnetic actuator is reduced or interrupted in accordance with the instruction of the control unit, and accordingly, the first communication channel is closed and the second communication channel is opened. In FIG. 7, the negative section of the valve opening degree graph means that the first communication channel is closed and the second communication channel is opened.

However, if the above state is maintained, the pressure of the crankcase becomes equal to the discharge pressure, and as a result, the operation of the compressor is stopped. Therefore, when the suction pressure reaches the target value, the current is applied to the actuator again or increased to have an appropriate opening degree. Even in this case, the opening degree of the valve shows a behavior of converging ultimately to the target value while repeating the increase and decrease based on the target value.

In the past, a separate orifice flow path is formed in order to mitigate the pressure rise of the crankcase due to the refrigerant leaking between the cylinder and the piston during the compression process, which has acted as a cause of efficiency deterioration. However, in the embodiment, since the suction pressure can be controlled as intended, the orifice flow path described above can be omitted or minimized to minimize the decrease in efficiency.

In addition, since the control section is largely biased to control the opening degree of the first communication channel, the section for inducing the discharge pressure to the crankcase is minimized. In other words, since the amount of refrigerant that has already been compressed, which is used to adjust the inclination angle of the swash plate, is minimized, an additional increase in efficiency can be expected.

FIG. 8 is a block diagram schematically showing a control system of a vehicle air conditioner having the above control device for controlling the compressor. Referring to FIG. 8, a control unit 200 of the air conditioner includes a set temperature input unit 201 which sets a desired temperature by the user, an outside air temperature sensor 202 which measures the temperature of the outside air, an evaporator outlet temperature sensor 203 which is provided in the air conditioner and measures an outlet temperature of an evaporator during a cooling cycle, an inside air temperature sensor 204 which measures the indoor temperature of the vehicle, and an insolation sensor 205 which measures the load by direct sunlight. The control unit 200 controls the operation of the air conditioner on the basis of the factors measured or input from above-described components.

In addition, the control unit 200 further includes an air conditioner door driving unit 210 which controls an actuator motor 222 for operating a temperature control door provided within the air conditioning system 220. Accordingly, the control unit 200 controls the temperature control door provided in the air conditioner on the basis of the above-described input value and various measured values and maintains the temperature of the interior of the vehicle at an input set temperature. In addition, the control unit 200 is configured to communicate via wired and wireless communication means so as to transmit and receive signals from an engine control unit 300 mounted in the vehicle.

The engine control unit 300 is connected to an engine 310 and is connected a pedal sensor 312 which measures how much an accelerator pedal is pressed. The engine control unit 300 controls the operation of the engine in accordance with a signal measured and generated by the pedal sensor. Heat generated from the engine during this process can be used to control the indoor temperature by a coolant circulation circuit (not shown).

On the other hand, a compressor control device 400 for controlling the compressor as described above may be provided separately from the air conditioner control unit 200. The compressor control device 400 is configured to be connected to the air conditioner control unit 200 and the engine control unit 300 so as to transmit and receive signals with each other. The compressor control device 400 controls the operation of the compressor on the basis of the measured values provided from the respective control units.

Specifically, the compressor control unit 400 includes a valve control unit 410 for controlling the suction pressure of the refrigerant discharged through the compressor, a clutch control unit 420 for controlling the operation of the clutch provided in the compressor, a compressor torque management unit 430 for controlling the torque transmitted to the compressor through the clutch, and an abnormality detection unit 440 for checking the operation status of the compressor.

Also, the compressor control unit 400 further includes a valve driving unit 450 for controlling the control valve and a clutch driving unit 460 for operating the clutch on the basis of the signals provided from the above components. The valve driving unit 450 controls the opening degrees of the first and second communication channels by controlling a current applied to the electromagnetic actuator provided in the control valve. The clutch driving unit 460 control the current applied to a coil provided in the clutch assembly such that the electromagnetic force can be maintained in the clutch assembly by as much as the torque transmitted to the rotational shaft 40 of the compressor.

Here, the valve driving unit and the clutch driving unit control the operation of the compressor in consideration of pieces of information transmitted from the various control units and management units provided in the control device 400. Each of the control unit and the management unit controls the operation of the compressor on the basis of values measured by using a suction pressure sensor 401 and a discharge pressure sensor 402 provided in the compressor, and a speed and stroke sensor 403 of the compressor.

Here, the values measured through the sensors include both the suction pressure and the discharge pressure. However, as described above, the suction pressure is used to control the stroke of the piston. That is, the stroke of the piston is controlled by varying the opening degree of the first communication channel according to a difference between the measured suction pressure and the target suction pressure.

In addition, the compressor control device may be installed in the housing of the compressor, and each of the provided sensors may also be directly mounted on the compressor. The compressor control device may be connected to the control unit 200 or the engine control unit 300 through a communication means provided in the vehicle, for example, CAN or LIN BUS, etc.

In some cases, as shown in FIG. 9, it is possible to consider that the valve control unit 410, the compressor torque management unit 430, the abnormality detection unit 440, and a valve driving unit 450′ form a portion of the air conditioner control unit 200, and only the suction pressure sensor and stroke sensor are arranged in the compressor. In addition, in the embodiment shown in FIG. 8, an example in which the clutch control unit, the compressor torque management unit, and the abnormality detecting unit are added or excluded as necessary may be considered.

As described above, the valve control unit 410 determines the discharge amount, that is, the stroke of the piston on the basis of the difference between the measured suction pressure and the target suction pressure. The valve driving unit controls the operation of the electromagnetic actuator provided in the control valve in accordance with the determined stroke. During this process, the target suction pressure is determined by the air conditioner control unit 200 and is calculated on the basis of information which includes the set temperature, the outside air temperature, etc., transmitted to the compressor control unit 400. FIG. 10 is a flowchart showing a process of controlling the suction pressure through the valve control unit.

Referring to FIG. 10, an inside air temperature Tp is measured by the air conditioner control unit where the control is started. After determining whether the measured Tp is the same as a predetermined set temperature Ts, if they are the same, the inside air temperature is measured again after a predetermined time has elapsed. If the measured Tp is not the same as the Ts, it is determined that the control of the inside air temperature is required.

Here, a cause of the difference between the Tp and the Ts is determined. If the user input is determined to be the cause, the input temperature is set to a new Ts. If there is a difference between the set temperature and the inside air temperature even though there is no user input, it is determined that the difference is caused by external causes.

Then, the Tp and the Ts are compared. If the Tp is greater than the Ts, cooling is required. Therefore, the target suction pressure Ps is reset to a lower value. If the Tp is lower than the Ts, it is necessary to reduce the refrigerant discharge amount of the compressor because cooled is being excessively performed. Therefore, in this case, the target Ps is reset to a higher value.

The thus reset target Ps is compared with the actual Ps. When the target Ps is greater than the actually measured Ps, the Ps must be controlled to be higher. Therefore, the control valve is controlled to reduce the opening degree of the first communication channel. Specifically, the valve body is moved toward the top of FIG. 2. If the target Ps is less than the actual Ps, the Ps must be controlled to be lower. Therefore, the control valve is controlled to increase the opening degree of the first communication channel. Specifically, the valve body is moved toward the bottom of FIG. 2.

After controlling the control valve, the actual Ps is measured again and it is checked whether the Ps reaches the target value. If a difference between the Ps and the target value still occurs, the process is repeated. If the Ps and the target value are the same, the control is terminated.

The compressor torque management unit calculates a current compressor torque based on the suction pressure, the discharge pressure, the operating speed of the compressor, and the stroke information of the piston. In this case, the torque may be calculated by the following equation.

$\begin{matrix} {{Torque} = {{{\frac{60}{2\pi \; N_{c}} \cdot \frac{n}{n - 1}}P_{s}v_{S}{\overset{.}{m}\left\lbrack {\left( \frac{P_{d}}{P_{s}} \right)^{\frac{n - 1}{n}} - 1} \right\rbrack}} + T_{loss}}} & {{Equation}\mspace{14mu} (1)} \end{matrix}$

The thus calculated torque value is transmitted to the engine control unit to precisely control the engine load for the compressor torque. In addition, the torque value may be used to control the clutch. That is, since the current applied to the clutch can be controlled based on the torque value, the clutch power consumption is controlled according to the compressor torque. It is possible to increase engine efficiency by precisely controlling the engine load through the compressor torque calculation and to reduce the clutch power consumption by controlling the current applied to the clutch in accordance with the compressor torque.

In the meantime, the abnormality detection unit may be operated by external commands or at a predetermined frequency, and detects whether the compressor is abnormal or not, as with the torque calculation unit, on the basis of values such as the suction pressure, the discharge pressure, the operating speed of the compressor, and the stroke of the piston, and like the. Here, the generated data may be transferred to the engine control unit and used in the operation of the engine.

Based on the respective data, it is possible to check whether there is an abnormality in the clutch or control valve provided in the compressor. When problems are detected as a result of the checking, the abnormality detection unit transmits the abnormality of the corresponding component to the engine control unit or another control unit of the vehicle so that the user can take appropriate actions.

Although the preferred embodiments of the present invention have been described above by way of example, the scope of the present invention is not limited to these specific embodiments, and can be appropriately changed within the scope described in the claims. For example, the suction pressure sensor 401 may be disposed in any one of the suction chamber of the compressor, the outlet end of the evaporator, and a refrigerant pipe between the evaporator and the compressor. In addition, the target suction pressure may be determined not only by the control unit 200 for the vehicle air conditioner but also by the compressor control unit 400.

In addition, the actuator described in the above embodiments is not limited to solenoid actuators. The actuator may be replaced by, for example, a stepper actuator, a direct current actuator or a piezoelectric actuator. 

1. A control device of a compressor, the control device comprising: a piston which reciprocates by a swash plate; a crankcase for receiving the swash plate which is mounted such that an inclination angle thereof with respect to a rotational shaft is variable; a discharge chamber from which a compressed working fluid is discharged; a suction chamber for sucking the working fluid to be compressed; a first communication channel for connecting the suction chamber and the crankcase, a second communication channel for connecting the discharge chamber and the crankcase; a control valve which selectively opens and closes the first communication channel and the second communication channel; a suction pressure sensor for measuring a pressure of the suction chamber; a valve control unit for controlling an opening degree of the first communication channel and the second communication channel within the control valve by comparing a measured suction pressure value by the suction pressure sensor and a target suction pressure; and a valve driving unit for operating an actuator which moves a valve body of the control valve to a determined position from the valve control unit to achieve the target suction pressure.
 2. The control device of claim 1, wherein information on an outside air state and on a set temperature of an outlet of an evaporator is provided from a control system of a vehicle air conditioner to the valve control unit.
 3. The control device of claim 1, wherein, when cooling is required, the valve control unit sets the target suction pressure to be lower than the measured suction pressure.
 4. The control device of claim 3, wherein, when target suction pressure is lower than the measured suction pressure, the valve driving unit increases the opening degree of the first communication channel.
 5. The control device of claim 4, wherein, when the first communication channel is at least partially opened, the second communication channel is in a closed state.
 6. The control device of claim 1, further comprising a transmitter-receiver for transmitting and receiving a signal to and from a control system of a vehicle air conditioner, wherein the valve control unit and the valve driving unit are provided separately from the control system of the vehicle air conditioner.
 7. The control device of claim 1, wherein the valve control unit and the valve driving unit are provided integrally with a control system of a vehicle air conditioner.
 8. The control device of claim 1, further comprising: a secondary sensing means for sensing at least any one of a discharge pressure, a stroke of the piston, and an operating speed of the compressor; and a compressor torque management unit which determines torque required to drive the compressor on a basis of the measured suction pressure and information from the secondary sensing means.
 9. The control device of claim 8, wherein the valve control unit provides the torque determined to an external control device.
 10. The control device of claim 1, further comprising: a secondary sensing means for sensing at least any one of a discharge pressure, a stroke of the piston, and an operating speed of the compressor; and an abnormality detection unit which detects whether the compressor is abnormal or not on a basis of the measured suction pressure and information from the secondary sensing means.
 11. The control device of claim 8, wherein the compressor further comprises an electronic clutch means which selectively transmits rotational torque to the rotational shaft, and wherein the control device of the compressor further comprises a clutch control unit which controls an operation of the electronic clutch means by selectively transmitting the rotational torque to the rotational shaft in accordance with the torque determined by the compressor torque management unit.
 12. A control valve comprising: a casing in which a space portion is formed therewithin and an electronic actuator is provided on one side end thereof; a valve body which is mounted to move within the casing; a first through hole which communicates with the space portion of the casing and a suction chamber of a compressor on which the valve body is mounted; second and third through holes which communicate with the space portion of the casing and a crankcase of the compressor on which the valve body is mounted; and a fourth through hole which communicates with the space portion of the casing and a discharge chamber of the compressor on which the valve body is mounted, wherein the second and third through holes are selectively opened and closed while the valve body moves along a longitudinal direction of the valve body.
 13. The control valve of claim 12, wherein the first and fourth through holes remain in an open state regardless of a position of the valve body.
 14. The control valve of claim 13, further comprising at least one filter which is installed in at least any one of the first and fourth through holes.
 15. The control valve of claim 12, wherein the space portion comprises a large diameter portion having a relatively large inner diameter and a small diameter portion having a relatively small inner diameter, and wherein the second through hole disposed relatively adjacent to the first through hole is disposed in the large diameter portion.
 16. The control valve of claim 15, wherein the third through hole disposed relatively adjacent to the fourth through hole is disposed in the small diameter portion.
 17. The control valve of claim 12, wherein, when the third through hole is at least partially opened, the second through hole remains in a fully closed state.
 18. The control valve of claim 15, wherein the valve body comprises a stepped portion facing an interface between the large diameter portion and the small diameter portion, and wherein an internal flow path extending from the stepped portion to an outer surface of the valve body is further formed.
 19. The control valve of claim 15, wherein the valve body comprises a tapered surface on a surface facing the second through hole or the third through hole.
 20. A compressor comprising: the control valve of claim 12; a rear housing in which the control valve is received and in which the suction chamber and the discharge chamber are formed respectively; a cylinder housing which comprises a plurality of cylinder bores radially formed therein and is coupled to the rear housing; and a front housing which is coupled to the cylinder housing and comprises the crankcase in which a swash plate is disposed therein, wherein a first communication channel which communicates the suction chamber and the crankcase is defined by the cylinder housing, the rear housing, the second through hole, and the first through hole, and a second communication channel which communicates the discharge chamber and the crankcase is defined by the cylinder housing, the rear housing, the fourth through hole, and the third through hole.
 21. The compressor of claim 20, wherein the first communication channel and the second communication channel are formed separately and have no overlapping section. 